Functional magnetic resonance imaging of binocular interactions in visual cortex in strabismus.

PURPOSE: To observe changes in primary visual cortical activation associated with perceptual suppression in individuals with strabismus, using functional magnetic resonance imaging (fMRI).

METHODS

In Phase 1, pilot data were collected from 1 control and 8 strabismic participants, including 5 with amblyopia. In Phase 2, results were collected from 7 participants with strabismus (2 recalled and 5 new), including 2 with amblyopia. fMRI compared primary visual cortex activation in two conditions: visual stimuli presented to both eyes, to evoke perceptual suppression of one eye in individuals with strabismus, and visual stimulation presented only to one eye.

RESULTS

Visual cortical activity modulations positively correlated with perceptual suppression were seen in 3 of 5 non-amblyopic Phase 2 study participants, but not in amblyopic subjects.

CONCLUSION

Cortical activity modulations correlated with modulation of strabismic suppression are detectable in non-amblyopic individuals using fMRI, suggesting a neural basis for strabismic suppression in primary visual cortex.